1. Technical Field
The invention relates to a plain bearing shell for supporting a crankshaft or a camshaft, or as a connecting rod bearing shell of an engine, the plain bearing shell comprising a radially outward protruding holding projection in the region of the separating surface of the plain bearing shell.
2. Background Information
An approach that has been known and commonly employed for some time involves forming radially outward protruding holding projections or cams in the region of the separating surfaces of crankshaft plain bearing shells used in internal combustion engines. They serve first of all as an installation aid that enables the plain bearing shells to be correctly positioned and installed in the engine block. However, they also prevent the plain bearing shells from twisting in the installed position during engine operation, either in a circumferential or axial direction.
An approach that has been known for some time involves using a stamping tool to form the holding projections in the region of the separating surfaces in the form of radially outward protruding release openings, said stamping tool being applied radially inward, that is, in the direction from the sliding surface of the plain bearing shell. However, this method of forming the holding projections has proven to be disadvantageous in that, in the region of the sliding surface or support surface, an opening facing the separating surface is created which has sharp edges that must then be rounded off by an elaborate process, and that in any case create a gap in the sliding surface.
German Patent No. DE 32 30 700 C 2 has already put forward the proposal to create the holding projection without forming a gap in the sliding surface, that is, without affecting the sliding surface, by an approach in which the associated separating surface of the plain bearing shell is compressed in a radially and axially delimited region such that, with an appropriate counter-holding action, material is deformed radially outward from the inner sliding surface, thereby forming the holding projection. It is of course understood here that the bearing shell must also be supported in the region of its outer side by an appropriate tool. In plain bearing shells with a holding projection produced in this manner, the compressed surface of the holding projection is necessarily situated lower than the associated separating surface of the plain bearing shell. In addition, the total projection is lower, that is, further removed from the plane of the associated separating surface than is the case, for example, in the method referred to above. This means that the bearing shell receptacle, for which of course a recess matching the projection must be provided, must undergo more elaborate and expensive machining, that is, in order to achieve greater depth. For this purpose, so-called side-milling cutters must be employed which, due to the requisite greater depth of formation of the recess for the bearing receptacle, must be of larger size and work at greater depth. In addition, a plain bearing shell of this type proves to be disadvantageous during assembly since the lower-lying holding projection relative to the separating surfaces of the plain bearing shell is not easily visible when the one views the separating surface, or, depending on the orientation, is itself not visible at all. The plain bearing shell must be rotated by hand and oriented so as to make the position of the holding projection discernible.
Starting from the above conditions, the objective on which the present invention is based includes in creating a plain bearing shell of the species which can be produced economically, in which the radial inner sliding surface is not affected during production, and in which the disadvantages described above do not occur.